1. Field of the Invention
The present invention relates to mobile communication systems, and more particularly to a method and apparatus for controlling a packet terminating call in a mobile communication system.
2. Discussion of the Related Art
Generally, a general packet radio service (GPRS) network represents a wire network of a radio service provider for providing a packet service. A related-art communication network for providing a packet service is shown in the block diagram of FIG. 1.
The FIG. 1 network includes a gateway GPRS support node (GGSN) 110, a serving GPRS support node (SGSN) 120, a home location register (HLR) 130, a base station controller (BSC) 140, and a base station (BS) 150.
The GGSN 110 performs a function of a gateway for interworking between the GPRS network 10 and the Internet 20 or an external packet network (not illustrated). The SGSN 120 is connected to the GGSN 110 through the GPRS network 10, manages the mobility of a mobile terminal (MT) 30 in a packet mode, and performs a function of a packet switch. The HLR 130 is connected to the GGSN 110 and the SGSN 120, and manages subscription information and location information of a subscriber. The BSC 140 controls and manages the BS 150, and the BS 150 manages radio resources and transfers data by allocating a traffic channel. Also, the MT 30 denotes a subscriber's terminal that can receive a packet service.
A general packet terminating call process in the related-art communication network of FIG. 1 will now be explained. If a packet data protocol packet data unit (PDP PDU) is received from the Internet 20 or another external packet network, the GGSN 110 checks whether a PDP context for a PDP address exists in the PDP PDU. If it is checked that the corresponding PDP context exists, the GGSN performs a first packet terminating call process that encodes the received PDP PDU and transfers the encoded PDP PDU to the corresponding SGSN 120 to which the corresponding terminating subscriber belongs.
If it is checked that the corresponding PDP context does not exist, the GGSN performs a second packet terminating call process that determines whether to proceed with a terminating process of the received PDP PDU based on static information of the subscriber.
FIG. 2, the manner in which the second packet terminating call process is performed. First, the GGSN 110 judges whether the static information for the PDP address of the received PDP PDU exists based on its own database when the PDP PDU is received (step S201). If so, the GGSN transmits a “Send Routing Info for GPRS” message for querying the HLT 130 about the location information of the terminating subscriber (step S202). In response to the “Send Routing Info for GPRS” message, the HLR 130 transmits a “Send Routing Info for GPRS Acknowledgement” message for providing an address of the corresponding SGSN 120 to which the terminating subscriber belongs to the GGSN 110 (step S203).
Next, the GGSN 110 attempts a packet terminating call request by transmitting a “PDU Notification Request” message to the SGSN 120 based on the received address (step S204). The SGSN 120 responds to the “PDU Notification Request” message by transmitting a “PDU Notification Response” message to the GGSN 110 (step S205), and then requests a packet terminating call connection by transmitting a “Request PDP Context Activation” message to the corresponding mobile terminal 30 of the terminating subscriber through the BSC 140 and the BS 150 (step S206).
The mobile terminal 30 performs a mutual PDP context activation procedure with the GGSN 110 according to the request (step S207), and then receives the received PDP PDU from the GGSN 110 (step S208).
When the communication network as shorn in FIG. 1 intends to set a packet terminating call for providing a PDP PDU to mobile terminals, a certain mobile terminal does not know information on the PDP PDU related to the packet terminating call set request at all. Thus, it should accept a set request for the corresponding packet terminating call in order to receive the PDP PDU. For the first time after the packet terminating call is set, the mobile terminal can receive the PDP PDU from the GGSN, and confirm the type of the received PDP PDU.
According to a result of confirmation, the mobile terminal can maintain or release the set call. That is, the mobile terminal can use the packet radio service in a passive manner. Thereafter, if PDP PDUs of the same type as the above-described PDP PDU is continuously received, the mobile terminal should repeatedly perform a call release procedure. Thus, it may not receive a packet radio service of a desired type. Continuous receipt of the PDP PDUs of such a non-desired type may simultaneously occur in all the mobile terminals of the GPRS network, or may be intentionally produced by an ill-intentioned Internet user.
The related-art technique as described above therefore has at least the following problems.
First, the mobile terminal may continuously receive PDP PDUs of a non-desired type, and this causes the GGSN to repeatedly inquire of the HLR about subscriber information and location information in order to provide the PDP PDUs to the corresponding mobile terminals, thereby producing a great load.
Second, a call release procedure according to the PDP PDUs of a non-desired type is repeatedly performed, and this causes waste of wire/radio resources.
Third, the mobile terminal cannot actively use the packet radio service.
Fourth, the degree of occupation of a specified mobile terminal or terminal group becomes high by an ill-intentioned Internet user, and this causes the performance of the whole system to deteriorate.